1. Technical Field
The disclosure relates to heat dissipation fans, and particularly to a centrifugal fan for dissipating heat generated by an electronic component.
2. Description of Related Art
Electronic components operating at high speed generate excessive heat which must be removed efficiently to ensure normal operation. Typically, a fan is used in combination with a heat dissipation device to produce an airflow in order to remove heat from the electronic components. Many portable electronic systems, such as a laptop computer or a notebook computer, are crammed with electronic components. There is little free space inside the computer. Accordingly, a centrifugal fan which requires only a small space for installation is generally used.
The centrifugal fan includes a housing and an impeller received in the housing. The housing is usually made of plastic material. An air inlet is defined in a central portion of a bottom wall of the housing. A bracket is located in the air inlet for supporting the impeller thereon. The bracket requires higher strength, and is usually made of metallic material. The bracket includes a chassis, a tube extending upwardly from the chassis, and a plurality of ribs extending outwardly from an outer periphery of the chassis. A through hole is defined in a distal end of each of the ribs. A plurality of screw holes corresponding to the through holes of the ribs are defined in the bottom wall of the housing around the air inlet. The bracket is connected to the housing via bolts, which are respectively extended through the through holes of the ribs and screwed into the screw holes of the bottom wall. The impeller is mounted around the tube of the bracket via a shaft rotatably received in the tube.
During operation of the centrifugal fan, the impeller rotates at high speed to generate an airflow. The impeller is liable to cause the bracket to vibrate with respect to the bottom wall of the housing. Since the housing is made of plastic material and the bottom plate is usually thin, each screw hole is short, and only a few turns of a screw thread can be formed on an inner wall of the screw hole. Thus, after the bolts are screwed into the screw holes, only a few turns of a screw thread of each bolt can engage with the screw thread of the corresponding screw hole. This means the bolts may easily disengage from the screw holes of the bottom wall when the centrifugal fan has operated for a long time.
It is thus desirable to provide a centrifugal fan which can overcome the described limitations.